1. Technical Field
The present disclosure relates to a method of manufacturing transfer sheet and a transfer sheet.
2. Description of Related Art
Transfer sheets have been widely used for printing images on materials such as clothes, ceramics, and plastics. A typical transfer sheet has a configuration such that a colorant layer including an objective image formed by an image forming apparatus, such as color laser printer or inkjet printer, is overlaid on a sheet-like base material having releasability, and an adhesive layer is further overlaid on the colorant layer. By bringing the adhesive layer of the transfer sheet into contact with a target medium, onto which the objective image is to be formed, upon application of pressure or heat, the objective image is transferred onto the target medium. The base material is peeled off from the target medium thereafter.
Various methods for manufacturing transfer sheet have been proposed so far. In some proposed methods, an adhesive layer is formed even on non-image image area. The adhesive layer formed on non-image area may undesirably deteriorate with time and disturb the color and gloss of the target medium. In particular, the adhesive layer formed on non-image area on clothes, such as T shirts, may undesirably give rough texture to the clothes.
Thus, in some proposed methods, an adhesive layer is removed from non-image area. For example, some methods propose to cut off non-image area from a transfer sheet using a cutting plotter. As another example, Japanese Patent Application Publication No. 2010-99940 proposes a method in which negative image is pressed against a positive image upon application of heat to obtain a transfer sheet from which non-image area is removed. As another example, Japanese Patent Application Publication No. 2010-99940 proposes a method in which negative image is pressed against a positive image upon application of heat to obtain a transfer sheet from which non-image area is removed.
When an objective image includes a high-lightness color portion formed of micro dots or a microscopic pattern, it may be technically difficult to precisely transfer the objective image onto a target medium. The reason is as follows.
FIG. 1 is a conceptional view of a dot structure in accordance with area coverage modulation. Typical electrophotographic image forming apparatuses employ area coverage modulation that expresses gradation by variations of dot size. A high-lightness color is formed of micro dots as illustrated in FIG. 1.
FIG. 2 is a cross-sectional view of a related-art transfer sheet having a high-lightness color toner image and an adhesive layer thereon. Referring to FIG. 2, in a related-art transfer sheet 11, a high-lightness color toner image 14 is formed on a release layer 22 of a release sheet 2 and an adhesive layer 16 is further formed on the high-lightness color toner image 14. The high-lightness color toner image 14 is to be transferred onto a target medium by adhering the adhesive layer 16 to the target medium.
Since the contact area of the high-lightness color toner image 14 with the adhesive layer 16 is small, these layers may be weakly bind to each other. As a result, it is likely that the adhesive layer 16 is undesirably peeled off by external force and the high-lightness color toner image 14 is not reliably transferred onto the target medium.
Since the dot area of the high-lightness color toner image 14 is small, the area of the adhesive layer 16 is also small. As a result, the high-lightness color toner image 14 may be fixed on a target medium only weakly. When the release sheet 2 is peeled off after the transfer sheet 1 is pressed against the target medium upon application of heat and pressure, it is likely that a part of the high-lightness color toner image 14 remains on the release sheet 2 or that transferred onto the target medium easily peels off by external force.
When an objective image includes a high-lightness color portion formed of micro dots or a microscopic pattern, it may be technically difficult to precisely transfer the objective image onto a target medium.